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2 years ago

Phosphoric acid has a pka of 2.1. at what ph will 75% of phosphoric acid be in the conjugate base form?

Chemistry

2 answers:

Colt1911 [192]2 years ago

8 0

Answer:

pH is 2.58

Explanation:

The pH of the buffer made from the mixture of phosphoric acid (H₃PO₄) and its conjugate base form (H₂PO₄⁻) follows the Henderson-Hasselbalch equation:

pH = pka + log [H₂PO₄⁻] /[H₃PO₄]

If 75% of the buffer is in the conjugate base form (H₂PO₄⁻), 25% will be as H₃PO₄. Replacing to find pH:

pH = 2.1 + log [75%] /[25%]

pH = 2.58

pH is 2.58

EleoNora [17]2 years ago

5 0

solution:

$from henderson hasselbalch equation\\pH=pka+log[\frac{conjugate}{acid}]\\given[\frac{conjugate base}{acid}]\\=\frac{75}{25}=3\\PH=2.1+log3\\pH=2.1+0.5=2.6$

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In 1-2 sentences, explain why weather can be predicted only as probable, not definite. (2 points) Plaese help me

anyanavicka [17]

Weather can be predicted only as probable, not definite because the daily weather conditions depends on winds and storms.

It is common observation that weather forecasts are often given as a probability and never in definite terms.

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The temperature of the earth's atmosphere changes frequently hence weather conditions also change frequently.

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2 years ago

While hiking in the woods, you see a brown, rotting apple lying on the ground. What changes is the physical properties of the ap

mojhsa [17]

Answer:

The change in color.

Explanation:

The apple turn brown in color because of the oxidation process. When the oxygen and water molecules in air react with it, oxidation take place. The oxidation process is very efficient in ambient temperature.

For example, if the peal off apple is placed into the refrigerator it take a time to got oxidize and turn brown, but if it is placed in room temperature it quickly turn brown.

when oxygen is react with peel off apple , it trigger the polyphenol oxidase enzyme to oxidize the phenolic compound and quinones are formed which then react with amino acids and produced brown color.

3 0

2 years ago

Item 5 A solution of methanol, CH3OH, in water is prepared by mixing together 128 g of methanol and 108 g of water. The mole fra

Basile [38]

Answer:

Mole fraction of methanol will be closest to 4.

Explanation:

Given, Mass of methanol = 128 g

Molar mass of methanol = 32.04 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{128\ g}{32.04\ g/mol}$

$Moles\ of\ methanol = 3.995\ mol$

Given, Mass of water = 108 g

Molar mass of water = 18.0153 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{108\ g}{18.0153\ g/mol}$

$Moles\ of\ water= 5.995\ mol$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ methanol=\frac {n_{methanol}}{n_{methanol}+n_{water}}$

$Mole\ fraction\ of\ methanol=\frac{3.995}{3.995+5.995}=0.39989$

Mole fraction of methanol will be closest to 4.

5 0

2 years ago

A gas balloon has a volume of 80.0 mL at 300K , and a pressure of 50.0 kPa. if the pressure changes to 80.0 kPa and the temperat

stellarik [79]

Answer: 53.3

Explanation:

V2=(T2 x P1 x V1)/(T1 x P2)

(320x50x80)/(300x80)

53.3

3 0

2 years ago

If the mass percentage composition of a compound is 72.1% Mn and 27.9% O, its empirical formula is

mojhsa [17]

Answer:

MnO- Manganese Oxide

Explanation:

Empirical formula: This is the formula that shows the ratio of elements

present in a

compound.

How to determine Empirical formula

1. First arrange the symbols of the elements present in the compound

alphabetically to determine the real empirical formula. Although, there

are exceptions to this rule, E.g H2So4

2. Divide the percentage composition by the mass number.

3. Then divide through by the smallest number.

4. The resulting answer is the ratio attached to the elements present in

a compound.

Mn O

% composition 72.1 27.9

Divide by mass number 54.94 16

1.31 1.74

Divide by the smallest number 1.31 1.31

1 1.3

The resulting ratio is 1:1

Hence the Empirical formula is MnO, Manganese oxide

8 0

2 years ago